DrShaggford

I have a 94 XJ 4.0 and my coolant temps stay between 170 and 180!

A few months back I replaced the thermostat and thermostat housing. Coolant is clean and full and i have checked several times to make sure there is no air in the system.

Originally I thought it was a bunk thermostat so I replaced it with another Stant thermo and the same thing.

Forgot to mention that prior to changing the thermostat and housing it ran right about 209-210. Any ideas or suggestions would be greatly appreciated as my MPGs are suffering.

99 Purple XJ

I had the same exact problem as you i went through 4 thermostats till i realized let me try a different BRAND thermostat and it worked although for some reason the old one was good it never let it warm up try going with a different brand i tried autozone duralast and it worked

DrShaggford

That's really odd but for a couple bucks it couldn't hurt to try! I despise Autozone parts but if it worked for you I'll give that one a go first. Thank you much for the fast response!

99 Purple XJ

No problem it sucked not having heat in winter and running to rich all the time

DrShaggford

The really weird thing is I still put out heat like a mother f*****. I still need ti get my hands on an IR thermometer so I can see what my temp really is.

jomps

yeah try that because if its running at norm operate temp it could be temp sensor especially if your heater works right

DrShaggford

I was thinking the same thing ...I have a couple other temp sensors laying around that I could throw in too. But my gas mileage dropped as soon as my temps dropped so I'm fairly certain that it's not getting to temp.